Automatic radio-transmitted brake application and release signalling apparatus for railway trains



Nov. 22, 1960 E E, VQN BEHREN 2,961,640

AUTOMATIC RADIO-TRANSMITTED BRAKE APPLICATION AND RELEASE SIGNALLING APPARATUS FOR RAILWAY TRAINS Filed June 16, 1958 d19x/ a l ATTURNEM United, tares Fatenit O l' AUTMATEC RADIO-TRANSMITTED BRAKE AP- PLHCAHN AND RELEASE SIGNALLING APPA- RATUS FOR RAHLWAY TRAINS Edward E. von Beltran, St. Louis, Mo., assigner to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation o Pennsylvania Filed June 16, 1953, Ser. No. 742,339

19 Claims. (Cl. 349-48) This invention relates to automatic brake application and release signalling apparatus and more particularly to apparatus for automatically signalling the occurrence of a brake application and a brake release from one end of a train to the other by means of radio transmission.

ln the operation of railway freight trains of considerable length, when a brake application is initiated on the locomotive, the application of the brakes serially on successive cars throughout the train to the caboose may cause an extensive degree of so-called slack action, the shock of which can cause personal injury to crewmen in the caboose at the rear end of the train. t may also occur in freight trains of great length that a brake application may be initiated from the caboose by crewmen or by leaking hoses in the rear of the train without an application occurring on the locomotive or head end of the train and also without any indication thereof such that the engineer could immediately initiate a brake application at the locomotive to prevent a train separation.

According to the invention, there is provided an automatic radio-transmitted brake application and brake release signalling apparatus for railway trains wherein a iirst pneumatic switch device located on the locomotive operates responsively to a build-up of brake cylinder pressure on the locomotive to control a radio-transmitter on the locomotive to automatically send a signal to a radio receiver in the caboose to produce an audible signal to warn the crewmen therein that a brake application has been initiated from the locomotive and as a consequence that a brake application on the caboose is imminent. The apparatus also includes a second pneumatic switch device located on the caboose operative responsively to build-up of pressure in the brake cylinder on the caboose as a result of operation of the brake valve on the locomotive or operation of a valve device such as a back-up valve on the caboose, to control a radio transmitter on the caboose to automatically send a signal via radio transmission to a radio receiver on the locomotive to produce an audible signal thereon to indicate that a brake application has occurred on the caboose. The second pneumatic switch device also operates responsively to a release of pressure from the brake cylinder on the caboose as a result of operation of the brake valve, back-up valve, or leakage, to control the radio transmitter on the caboose to automatically radio transmit a signal to the locomotive to produce an audible signal thereon to indicate the release of the caboose brakes. An interlock switching means is also provided to prevent transmission of signals from either the locomotive or the caboose if the radio system is being utilized by members of the train crew for verbal communication purposes.

In the accompanying drawing, Fig. l is a diagrammatic view of a railway train showing radio transmission and receiver means, employed in this invention, located on the locomotive and on the caboose; and Fig. 2 shows partly in outline and partly in section the details of the signalling apparatus on the locomotive and on the caboose and its association with the tluid pressure braking system 2,961,640 Patented Nov. 22, 1960 on the train, together with the circuitry by which the signalling apparatus is associated with the radio transmission and receiving apparatus on the locomotive and caboose.

Description transceiver 2, are shown herein as a box with two attached antennae, one antenna being for transmission and the,

other for reception of radio signals. Referring to Fig. 2,'

the locomotive apparatus includes transceiver 1, microphone device 3, pneumatic switch device 4 and interconnecting circuitry hereinafter described.

Th-e pneumatic switch device 4 is connected by branch pipes 5 and 6 to the usual pneumatic train brake equipe ment including a brake, cylinder pipe 7 and brake cylinder 8 on the locomotive. In customary manner, the loco-I motive and each car is provided with a control valve 9; which may be the well-known AB valve or equivalent,l and an auxiliary reservoir 10. Each car also has a brake cylinder 8. A brake pipe 11 extends through all cars the length of the train, and the locomotive is provided with the usual brake valve 12 for controlling the supply of fluid under pressure from the main reservoir 13 to the brake pipe 11 on the locomotive via a pipe 14. Charging of the brake pipe to a normal pressure under the control of the brake valve effects operation of the control valve 9 to effect a release of the brakes on the locomotive and cars. Similarly, reduction of the pressure in the brake pipe under the control of the brake valve effects operation of the control valves 9 to cause application of the brakes on the locomotive and cars.

The pneumatic switch device 4 has a vibrator portion 15 and a pneumatic portion 16. Portion 16 comprises three casing sections 17, 18 and,19 with a diaphragm 20 of large diameterl clamped between the sections 17 and 18 as by a plurality of bolts 21 and a diaphragm 22 of small diameter clamped between the sections 18 and `19 by other bolts 21. The diaphragms 20 and 22 are spaced apart by a connecting follower 23 within a follower charnber 24 dened by the casing section 18 and the diaphragms 20 and 22. A brake cylinder chamber 25 is defined by the diaphragm 22 and casing section 19. A timing chamber 26 is defined by the diaphragm 20 and the casing section 17.

The brake cylinder chamber 25 is connected to the brake cylinder 8 on the locomotive via branch pipe 6 and brake cylinder pipe 7 so as to receive fluid under pressure from the brake cylinder when a brake application is made.

The timing chamber 26 is connected via a timing choke 27 to the branch pipe 5 which in turn is connected to the brake cylinder pipe 7 such that fluid under pressure will be supplied thereto from the brake cylinder during a brake application, said timing choke 27 delaying the supply of fluid to the timing chamber 26 such that pressure in said chamber is built up at a slower rate than the build-up of iluid pressure concurrently supplied to the brake cylinder chamber 25.

The left-hand diaphragm 20 subject to the fluid pressure in the timing chamber 26 is of larger diameter than the right-hand diaphragm 22 subject to the uid pressure inthe brake cylinder chamber 25. A spool-shaped element 2S xed on the follower 23 engages one end of a pivoted "5 Y` switch member 29 and causes ber 29 into and out of contact withi'a pivotedswitch member 30, the latter being biased to the position in which it is shown by a spring 31 and-being -yieldingly pivoted to the right when engaged by the switch member 29. Switch members 29 and 30 are mounted in insulated relation to the casing section 18 as by insulating pivot pins 32 and 33. Also, spring 33 isinsulated from switch member 30 and the casing section 18, in manner not shown. The vibrator portion 15 contains an electro-magnetic vibrator 34 of familiar construction consisting of two electro-magnetic coils 35 and 36 connected in parallel to each other, with the common terminals at one end being connected to a wire 37 extending to the microphone circuitry hereinafter described, and with the common terminals at the opposite end being connected to a resilient fiexible contact or armature 38. Contact 38 is biased so as toengage a stationary contact 39 which in turn is connected to the switch member 30. The contact 38 is so mounted adjacent coils 35 and 36 that upon energization of said coils, contact 38 will separate from the contact 39 and upon the consequent deenergization of said coils, inherent resiliency therein will return contact 38 into engagement with contact 39.

Referring to Fig. 2, the locomotive transceiver 1 is connected to the microphone 3 by interconnecting circuitry, hereinafter sometimes referred to as the signal input circuit, including a supply wire 40 leading from a source, such as a battery, indicated by terminals B and B+, via circuits, indicated by a broken line, within said transceiver 1, a return wire 41 connected to the switch member 29, a microphone wire 42, a battery return branch wire 43. A microphone cradle arm 44 acts as a switch lever contact to connect the supply wire 40 selectively to either the microphone wire 42 or the vibrator wire 37. The cradle arm 44 is biased by a spring 45 into engagement with a microphone contact 46 when the microphone 3 is not resting thereon. When the microphone 3 is in the cradle arm 44 the conducting portion 47 thereof is in contact with a vibrator contact 48 thereby electrically connecting the vibrator wire 37 to the supply wire 40. An insulator block 49 separates the conducting portion 47 of the arm 44 from the cradle portion 50.

As further shown in Fig. 2, the signalling apparatus on the caboose includes the mentioned transceiver 2, microphone device 51, pneumatic switch device 52 and interconnecting circuitry hereinafter described.

The pneumatic switch device 52 is connected by a brake cylinder branch pipe 53 to the brake cylinder 8 on the caboose.

The pneumatic switch device 52 comprises a vibrator portion 54 and a pneumatic switch portion 55. Portion 55 includes a diaphragm 56 clamped between two casing sections 57 and 58, as by a plurality of bolts 59. The easing section 57 and the diaphragm 56 define a timing chamber 60 which is connected via a choke 61 to the brake cylinder branch pipe 53. Casing section 58 and the diaphragm 56 define a switch chamber 62. Attached to the diaphragm 56 on the right-hand side thereof and extending through said switch chamber to a vented guide bore 63 in the casing section 58 is a diaphragm follower 64. A contact ring 65 is fixed in insulated relation on the zfollower 64, and a spring 66 biases the contact ring, follower 64 and diaphragm 56 to the left. A pair of iinger contacts 67 and 68 carried in insulated relation to casing section 58 are arranged on diametrically opposite sides of the contact ring 65 in such spaced relation that a predetermined movement of the follower 64 and thereby the contact ring 65 in the right-hand direction causes the contact ring 65 to electrically connect said iinger contacts. A plate 69 of insulating material insulates spring 66 from the casing section 58 so as tol prevent possible grounding of the contact ring 65 to the casing movement of switch mem- Y v548 through the spring 66. A battery return branch wire 70 is connected to the finger contact 68. A jumper wire 71 connects the finger contact 67 to a stationary vibrator contact 72 of the vibrator portion 54 of said pneumatic switch device 52.

The vibrator portion 54 is similar to the vibrator portion 15 of the pneumatic switch device 4 and contains an electro-magnetic vibrator 73 consisting of two electromagnetic coils 74 and 75 connected in parallel to each other and having their common terminals at one end connected to a vibrator wire 76 extending to the microphone circuitry hereinafter described. The common terminals of coils 74 and 75 at the opposite end are connected to a resilient flexible contact or armature 77. Contact 77 is biased so as to engage a stationary contact 72 which, as previously mentioned, is connected by wire 71 to the finger contact 67. The contact 77 is mounted adjacent coils 74 and 75 such that upon energization of said coils, contact 77 will be moved by magnetic attraction out of engagement with the stationary contact 72 and upon deenergization of said coils, inherent resiliency therein will return contact 77 into engagement with contact 72.

The circuitry included in the caboose apparatus com prises a supply wire 78 leading from a source, such as a battery, indicated by terminals B and B+ via circuits indicated by a broken line within said transceiver 2, a return wire 79 connected to both the microphone 51 and the battery return branch wire 70 previously described, and a microphone wire 80. A microphone cradle arm 81 is biased by a spring 82 into engagement with a microphone contact 83 when the microphone 51 is not resting thereon. When the microphone 51 is in the cradle arm 81, the conducting portion 84 thereof is in contact with a contact 85, thereby electrically connecting the wire 76 to the supply wire 78. An insulator block 86 separates the conducting portion 84 of the arm 81 from a cradle portion 87.

Operation The apparatus, as illustrated in Figs. 1 and 2, is in a normal condition with the train brakes released and the microphones 3 and 51 not in use but resting in their respective cradle portions of the cradle arms 44 and 81.

A brake application is initiated in the usual wellknown manner by manipulation of the brake valve 12 to vent the brake pipe 11, to effect a reduction of pressure therein resulting in operation of the control valves 9 to supply fluid under pressure to the brake cylinders 8 and thus cause a brake application on each car throughout the train. If the train is composed of a large number of cars` the application of the brakes on the cars progressing serially between the locomotive and the caboose requires suiiicient time for the signalling apparatus to forewarn crew members in the caboose of the application, such that they take any appropriate safety measures to prevent personal injury or equipment damage which could result on sudden unwarned braking.

On initiation of a brake application, the control valve 9 on the locomotive functions in a well-known manner to effect supply of fluid under pressure from reservoir 10 to the brake cylinder 8 via a pipe 88. Simultaneously with the supply of iiuid under pressure to pipe 88, the brake cylinder pipe 7 connected thereto supplies uid under pressure to the brake cylinder chamber 25 of the pneumatic switch device 4 by way of pipe 6. While fluid under pressure is supplied to brake cylinder chamber 25, it is simultaneously supplied via pipe 5 to the timing chamber 26 at a slower rate due to the effect of the choke 27. It can thus be seen that upon initiation of a brake application the relative rates of charging of chambers 25 and 26 is such as to create a differential fiuid pressure which effects movement of the diaphragms and follower 23 to the left such that the spool-shaped element 28 moves switch member 29 into engagement with the switch member 30. With the switch members 29 and '30 in engagement, a so-called warning" circuit is completed as will be hereinafter explained. After a predetermined time interval such as a few seconds,'as regulated by the size of the choke 27, the pressure in the timing chamber 26 builds up to equal that in chamber 25 at which time due to the effect of a spring 89 and the pressure in chamber 26 acting on the larger area of diaphragm 20, the diaphragms 20 and 22 and follower 23 are moved to the right to the normal position as shown, thereby causing the element 28 to separate the switch members 29 and 30 to open the warning circuit hereinafter described.

The warning circuit may be traced from the B+ supply at the transceiver 1 via a wire 90 through the internal circuitry broken line of the transceiver 1 to wire 40 and the conducting portion 47 of the cradle arm 44 and thence via the contact 48 (assuming the microphone 3 is resting in the cradle arm 44 to maintain the contact 48 in engagement therewith) to wire 37 and the electromagnetic coils 35 and 36, resilient contact 38, stationary contact 39, wire 91, closed switch members 30 and 29, battery return branch wire 41 and battery return wire 43 to the B- terminal at the transceiver 1. This just described warning circuit is intermittently closed and opened due to the operation of the vibrator 34. It will be seen that upon completion of the warning circuit, the coils 35 and 36 act to open the contacts 38 and 39 thereby breaking the circuit and deenergizing the coils to permit reclosing of the contacts to remake the circuit and again energize the coils, thus effecting an intermittent signal at the transceiver 1 where such signal is radiotransmitted to the transceiver 2 in the Caboose to warn crewmen there of the occurrence of the brake application on the locomotive. This signal is transmitted until the uid under pressure in the timing chamber 26 approximately equals that in the brake cylinder chamber 25 thereby effecting separation of the switch members 29 and 30 as previously explained.

As the brake application progresses serially through the cars of the train, the brakes on the caboose will begin to apply in the usual manner a short interval of time (of the order of 10 seconds for a 100 car train) following the initiation of a brake application on the locomotive, under the control of the control valve 9 thereon which elfects the supply of fluid under pressure from the auxiliary reservoir 10 to the brake cylinder 8 on the caboose. Simultaneously with supply of uid under pressure to the brake cylinder 8 on the Caboose, liuid under pressure is supplied via the pipe 53 and the choke 61 to the timing chamber 60 of the pneumatic switch device 52. The build-up of fluid pressure in chamber 60 causes the diaphragm 56 and follower 64 to move to the right such that the contact ring 65 passes between the finger contacts 67 and 68 engaging said contacts along flat indented surfaces 92 and 93 on the finger contacts of predetermined length to complete an answer signal circuit hereinafter described. Depending on the number of cars in the train, the answer signal will begin Vto be transmitted back to the locomotive either before or after the warning signal from the locomotive ceases. This is so because the timing of the warning signal circuit by switch device 4 is a fixed time which may be shorter r longer than the transmission time of the pressure reduction wave in the brake pipe 11 from the locomotive to the Caboose. When the fluid in chamber '60 reaches a certain pressure determined by the length of surfaces 92 and 93 and the resisting force of spring 66, the Contact ring 65 moves off the surfaces 92 and 93 to the right thereby interrupting the answer signal circuit.

The answer signal circuit may be traced lfrom the B+ supply at the transceiver 2, via wire 94 through the internal circuitry (shown in broken line) of the transceiver 2 and thence lto supply wire 78 to the conducting portion 84 of the cradle arm 81, the contact 85 (when the microphone 51 is resting in the cradle arm 81), wire 76 to the electro-magneticscoils 74 -and 75,- contact 77 engaging contact 72,` wire 71 to finger contact 67 and thence via the contact ring to contact linger 68 and the battery return branch wire and return wire 79 to the B terminal at the transceiver 3. The coils 74 and act similarly to the coils 35 and 36 of the vibrator 34 on the locomotive, to alternately open and close the contacts 77 and 72 such that the circuit current is of an intermittent nature to the transceiver 2 where the transceiver 2 operates to transmit a similar'intermittent signal to the transceiver 1 on the locomotive.

When a release of the brakes is initiated by operation of the brake valve 12 on the locomotive, the consequent restoration to normal pressure in the brake pipe 11 causes the control valve 9 on the locomotive to operate to vent fluid under pressure from the brake cylinder 8 on the locomotive. The control valves 9 on the intermediate cars and on the caboose or last car of the train also operate serially to ventY tiuid under pressure from the corresponding brake cylinders. Y

Coincident w1th the venting of fluid under pressure from the brake cylinder 8 on the locomotive, uid under pressure is vented at a rapid rate from the chamber 25 of pneumatic switch device 4 and at a relatively restricted rate from chamber 26 due to timing 'choke 27. Accordingly, due to the predominating force exerted on diaphragm 2) and follower 23 by the pressurein chamber 26, switch contact member 29 remains in the position in which it is shown in the drawing, that is out of contact with switch contact member 30. Consequently, the warning circuit on the locomotive is not established when the brake application is released on the locomotive.

As the pressure of duid in the brake cylinder on the Caboose begins to reduce, consequent upon the release of the brakes as just described, the pressure of fluid in chamber 60 will simultaneously reduce to permit the spring 66 to move the contact ring 65 to the left to reengage the surfaces 92 and 93 of the respective contact ngers 67 and 68 to again complete the answer signal circuit (previously described) to indicate to the engineer on the locomotive that the brakes on the rear ofthe train have started to release. The answer signal circuit `remains complete during a brake release until the pressure of uid in chamber 60 is reduced suiclently to permit the spring 66 to move the contact ring 65 to 'the left, off the surfaces 92 and 93, thereby interrupting the answer signal circuit.

It should be noted that when the microphone 3 on the locomotive is out of the cradle arm 44, the spring 4S `shifts the arm to a raised position, thereby disengaging the conducting ,portion 47 from the contact 48 and effecting engagement of said conducting portion 47 with the microphone contact 46 in 'a manner such that the warning circuit is interrupted and a locomotive microphone circuit is established.

The locomotive microphone circuit may be traced from the B| supply'at transceiver 1 via wire 90 through the internal circuitry of the transceiver 1 to the'supply wire 40 and thence to the conducting portion 47 of the cradle arm 44 in its raised position and thence from the microphone contact 46 via microphone wire 42 to the microphone 3 andthe battery return wire 43 to the B terminal at the transceiver 1. Establishment of the locomotive microphone circuit enables voice radio conversation at the microphone 3 to be transmitted via the transceiver 1 to the transceiverV 2 on the Caboose. When the microphone 3 is not in use, it is replaced on the cradle portion 5t) of the cradle arm 44 whereby the weight of the microphone moves the cradle arm to its lower position against the spring 45 to thereby disengage the microphone contact 46 and engage the contact 48 such that the warning circuit may be completed at the time a brake application is initiated.

The microphone 51 and the transceiver 2 on the caboose are operated similarly to microphone 3 and transceiver 1 on the locomotive in that when the microphone 51 is lifted from the cradle arm 89, the spring 82 raises said arm to interrupt the answer signal circuit at the contact 85 and establish a caboose microphone circuit at the microphone contact 83.

The caboose microphone circuit may be traced from the B+ supply at the transceiver 2 via wire 94 through the internal circuitry of said transceiver 2 to wire 78, the conducting portion 84 of the cradle arm 81 in its raised position, microphone contact 83, microphone wire 80, microphone 51 and the battery return wire 79 to the B- terminal at the transceiver 2. Establishment of the caboose microphone circuit enables voice radio conversation at the microphone 51 to be transmitted via transceiver 2 to a transceiver 1 on the locomotive. When the microphone 51 is not in use, it is replaced on the cradle arm 87 whereby the weight of the microphone moves the cradle arm to its lower position to disestablish the caboose microphone circuit and reestablish the answer signal circuit.

' Summarizing it can he seen that the apparatus here described operates upon initiation of a brake application to automatically transmit a signal to the caboose via the existing radio transmitters, producing an audible vibrating warning of such a brake application, and application of the brakes or release after application is similarly automatically transmitted from the caboose to the locomotive to indicate to the engineer the braking conditions at the caboose.

Having now described the invention, what I claim as new and desire to secure by Letters Patent, is:

l. For use with a fluid pressure brake apparatus on a train of cars comprising a locomotive and a rear car; a brake application and release signalling system comprising, in combination, a radio device on the locomotive, a radio device on the rear car, a source of supply of fluid under pressure on the locomotive, a source of supply of fluid under pressure on the rear car, a first brake cylinder on the locomotive and a second brake cylinder on the rear car, control means for controlling supply of fluid under pressure from said sources to said first and said second brake cylinder respectively, to effect a brake application, a first pressure switch means located on the locomotive and operative responsively to a supply of fluid pressure to said first brake cylinder means, warning circuit means including said first pressure switch means and operatively controlled by said first pressure switch means to render the radio device on the locomotive effective to transmit a signal to the radio device on the rear car, a second pressure switch means located on the rear car and operative responsively to a supply of fluid under pressure to said second brake cylinder on the rear car, and answering circuit means including said second pressure switch means operatively controlled by said second pressure switch means when fluid under pressure is supplied to the said second brake cylinder means on the rear car to render the radio device on the rear car effective to transmit a signal to the radio device on the locomotive.

2. A brake application signalling system for a train of cars of the type having a locomotive, a rear car or caboose, said system comprising a radio signal transmitter having a signal input circuit on the locomotive at the head end of the train, a radio signal receiver on the caboose at the rear of the train, signal control means in the said signal input circuit of said radio transmitter operative to pulsate the current in said circuit to cause transmission of a radio signal by said transmitter to said radio receiver, a source of fluid under pressure on the locomotive and cars, brake cylinder means on the locomotive and each car of the train, control means for controlling the supply of fluid under pressure from said source to said brake cylinder to effect a brake application, switch means on the locomotive operative to a closed position upon initiation of a brake application on 8 the train by said control means for causing said signal control means to operate, and timing means for opening said switch means to render said signal control means inoperative upon the expiration of a predetermined time interval following initiation of a brake application on the locomotive.

3. A brake application signalling system for a train of cars including a locomotive at the head end of the train and a caboose at the rear of the train, said system comprising the combination of an air brake system including a source of fluid under pressure on the locomotive and the caboose, a brake cylinder on the locomotive and a brake cylinder on the caboose operative to effect an application of the brakes on the locomotive and caboose respectively in response to the supply of fluid under pressure thereto from said source, control means for controlling the supply of fluid under pressure to said brake cylinders, a radio signal transmitter on the locomotive, a signal input circuit for said transmitter, a radio signal receiver on the caboose, a vibrator in the signal input circuit of the said radio transmitter operative to pulsate the current in said signal input circuit to cause the radio transmitter to correspondingly transmit a signal to the said radio receiver on the caboose, and normally open fluid pressure operated switch means operative to a closed position upon the supply of fluid under pressure to the brake cylinder on the locomotive upon initiation of a brake application for causing said vibrator to operate.

4. A brake application signalling system as defined in claim 3, further characterized in that the fluid pressure operated switch means comprises a diaphragm means arranged to be subject in opposing directions to the pressure of fluid supplied to the brake cylinder on the locomotive upon initiation of a brake application, and choke means for restricting the build-up of brake cylinder pressure on the locomotive in one direction on said diaphragm means whereby a differential pressure force is created to actuate the fluid pressure operated switch means to a closed position, and chamber means in which fluid pressure builds up via said choke means for effecting a balance of fluid pressure forces on said diaphragm and the consequent restoration of the switch means to open position at the expiration of a period of time predetermined by the size of said choke means following the initiation of the supply of fluid under pressure to the brake cylinder on the locomotive.

.5. Abrake application signalling system as defined in claim 3, further characterized in that the fluid pressure operated switch means comprises two operating diaphragms of differential area, a chamber at one side of one of said diaphragms for receiving fluid pressure in correspondence with the pressure supplied to the brake cylinder on the locomotive upon initiation of a brake application, a second chamber at one side of the other of said two diaphragms for also receiving fluid under pressure according to the pressure of fluid supplied to the brake cylinder on the locomotive, and choke means for delaying the build-up of fluid under pressure in said second chamber whereby to cause operation of the said switch means to a closed position upon initiation of a supply of fluid under pressure to the brake cylinder on the locomotive by reason of the differential fluid pressure forces acting on said diaphragms, and subsequently, after the expiration of a certain time predetermined by the size of said choke means in which the pressure in both of said chambers attains substantial equalization, to cause operation of the said switch means to an open position thereby to cause termination of operation of said vibrator.

6. For use with a train of cars of the type having a locomotive and a rear car, a brake application signalling system comprising a radio device on the locomotive and a radio device on the rear car, a source of supply of lluid under pressure on the locomotive and the rear car, a rst brake cylinder means on the locomotive, and

a second brake cylinder means on vthe rear car oper-ative upon supply of fluid under pressure thereto from said source to eflect a brake application on the locomotive and rear car respectively, control means for controlling supply of fluid under pressure to said first and second brake cylinder means, warning circuit means effective `when energized to cause said radio device on the locomotive to operate to transmit a warning signal to the radio device on the rear car, first pressure responsive means subject to the fluid under pressure in said first brake cylinder at a predetermined rate of supply immediately upon initiation of a brake application, sec- .ond pressure responsive means subject to supply of fluid under pressure in said first brake cylinder at a slower rate than said predetermined rate of supply after initiation of a brake application, and switch means included in said Warning circuit means operable responsively to a differential of'pressures acting in opposition to each other on said first pressure responsive means and said -second pressure responsive means to render said warning circuit energized and operable responsively to equal- ,ization of the pressures acting -in opposition to each other on said first and second pressure responsive means to render said warning circuit deenergized.

7. For use with a train of cars of the type having a locomotive and a rear car, a brake application and release-signalling system comprising in combination a radio device on the locomotive and a radio device on the rear car, a source of supply of fluid under pressure on the locomotive Vand the cars, a first brake cylinder means on the locomotive and a second brake cylinder means on the rear car operative upon the supply of fluid under pressure thereto from said source to effect a brake application on the locomotive and rear car respectively, control means for controlling the supply of fluid under pressure to said first and second brake cylinder means, warning circuit means effective when energized to cause said radio device on the locomotive to operate to transmit a warning signal t the radio device on the rear car, microphone circuit means effective when energized to cause said radio device on the locomotive to operate to transmit voice communication to the radio device on the rear car, first pressure responsive means subject to the fluid under pressure in said first brake cylinder at a predetermined rate of supply immediately upon initiation of a brake application, second pressure responsive means subject to fluid under pressure in said first brake cylinder at a slower rate than said predetermined rate of supply after initiation of a brake application, and switch means included in said warning circuit means operable responsively to a differential of pressures acting in opposition to each other on said first pressure responsive means and said second pressure responsive means to render said warning circuit energized and operable responsively to equalization of the pressures acting in opposition to each other on said first and second pressure responsive means after a vpredetermined time interval to render said warning circuit deenergized, and selector switch means for effecting energization of said microphone circuit and at the same time causing said warning circuit to be deenergized. l

8. A brake application signalling system for a train of cars including a locomotive at the head end and a caboose at the rear end of the train, said signalling systern comprising a radio signal transmitter on the locomotive, a radio signal receiver on the caboose, a signal input circuit for said radio transmitter, a microphone for connection to said signal input circuit for voice communication purposes, signal control means .connectable to said signal input circuit, brake cylinder means on the locomotive and rear car, a source of supply of fluid under pressure, control means for controlling the supply of fluid under pressure to said brake cylinder means to eflect a brake application, means including said signal control means responsive to the initiation of a brake application t T0 Vby an operator on the locomotive for causing said signal control means to operate,'and selector switch means effective in one position when said microphone is not in use for connecting said signal control means to said signal input circuit and effective in a second position when said microphone is in use to disconnect said signal control means from and to connect said microphone to said t signal input circuit.

9. A brake application signalling system for a train of cars including a locomotive at the head end of the train and a Caboose at the rear end of the train, said system comprising a radio signal transmitter on the caboose, a radio signal receiving device on the locomotive, a signal input circuit for said radio signal transmitter, a vibrator operative to effect a pulsating current in said signal input circuit to cause the said radio transmitter to transmit a radio signal to the radio receiving device on the locomotive, brake cylinder means on the caboose, a'source of supply of fluid underpressure, control ,means for controlling the supply of fluid under pressure to said brake cylinder means to eflect a brake application, and switch means operative responsively to the supply offluid under pressure to the said brake cylinder on the `Caboose incidental to a brake vapplication occurring von the Caboose for causing operation of said vibrator.

1,0.,A1brake application signalling system for 'a train of cars of the type including a locomotive at the head of the Vtrain and a .Caboose at the lrear of the train, said system comprising the combination of an air brake system including a source of supply of fluid under pressure, a brake pipe extending through the Vtrain normally charged with fluid under pressure from said source, brake cylinderzmeans on the locomotive and caboose and each car, and control means on the locomotive, Caboose and each car of the train effective in response to reduction of fluid pressure in the brake pipe under the control of an operator control means on the locomotive to cause supply of -fluid `under pressure from said source to said brake cylinders to Veffect a brake application which progresses serially from the head to the rear of the train, a radio signal transmitter on the caboose, a radio signal receiver on thelocomotive, a signal input circuit for said radio transmitter, a vibrator in said signal in-put circuit for effecting a pulsating current in said circuit to cause said radio transmitter to transmit a corresponding signal to the radio receiver in the locomotive, switch means included in said signal input circuit responsive to the application of th-e brakes on the caboose a predetermined time after initiation of the reduction of the pressure in the .brake pipe on the locomotive for causing said vibrator to operate to cause transmission by radio of a signal vfrom the said transmitter to the receiver on the locomotive whereby said receiver signals that the brake application has reached the rear of the train.

11. A brake application signalling system for use on :a train-of railway cars of the type having a locomotive, intermediate cars, and a rear car, said signalling system .including a brake pipe extending throughout the train, a source'of supply of fluid under pressure, and brake cylinders on each car to which fluid under pressure is supplied from said source tol effect a brake application responsive to the reduction of the pressure in the brake pipe at the locomotive, control means for controlling the pressure o-f fluid in said brake pipe, a radio signal trans- `mitter on the rear 'car of the train, a radio signal receiver fon the locomotive, a signal input circuit for said radio transmitter, vibrator means in said input circuit for controlling the input circuit to cause the radio transmitter to transmit asignal to the radio receiver, a fluid pressure operated switch means included in said signal input circuit operatively responsive to the pressure of fluid supplied to the brake cylinder on the rear car for causing said vibrator to operate, and timing means for causing said fluid presstire operated switch means to 'operate so as to terminate operation of said vibrator at a predetermined time after said vibrator begins to operate.

12. A brake application signalling system as claimed in claim ll, further characterized in that the fluid pressure operated switch means comprises a chamber to which fluid under pressure is supplied from said source according to the pressure of fluid in the brake cylinder on the rear car of the train, a diaphragm subject to a first predetermined pressure in said chamber for operating said switch means to closed position to thereby render said vibrator operative, choke means for restricting the build-up of pressure in said chamber means, said diaphragm being effective responsively to a second predetermined pressure higher than said rst predetermined pressure to cause opening of said switch means to thereby terminate operation of said vibrator.

13. A brake application signalling system as claimed in claim l2, further characterized in that said diaphragm operates responsively to the reduction of pressure in said chamber below said second predetermined pressure incidental to the release of pressure in the brake cylinder on the rear car to effect closure of the switch means to thereby cause said vibrator to operate, and subsequently upon reduction of the pressure in said chamber to below said first predetermined pressure to open said switch means and thereby cause termination of operation of said vibrator.

14. A brake application signalling system for use on a train of railway cars including a locomotive at the head end and a caboose at the rear end of the train, said system comprising an air brake system having a source of fluid under pressure, brake operating cylinders on each car to which uid under pressure is supplied from said source for effecting a brake application responsively to reduction of pressure of fluid in a brake pipe extending throughout the train, control means for controlling the pressure of fluid in the brake pipe, a radio signal transmitter and a radio signal receiver on the locomotive, a radio signal receiver and a radio signal transmtter on the caboose, a first signal input circuit for the radlo signal transmitter on the locomotive, first vibrator means on the locomotive controlling the said first signal input circuit of the radio transmitter on the locomotive, means included in said rst signal input circuit operatively responsive to the supply of fluid under pressure to the brake cylinder on the locomotive for rendering Asaid first vibrator means operative to cause the radio transmitter on the locomotive to transmit a corresponding signal to the radio receiver on the caboose to give warning of the imminence of the occurrence of a brake applicatfon on the caboose, a second signal input circuit for said radio transmitter on the caboose, second vibrator means on the caboose for controlling said second signal input circuit of the radio transmitter on the caboose, and means included in said second signal input circuit operatively responsive to the supply of fluid under pressure to the brake cylinder on the caboose for causing said second vibrator means on the caboose to operate to cause transmission of a signal by radio from the transmitter on the caboose to the receiver on the locomotive to indicate on the locomotive that the brake application is being effected on the caboose.

15. For use on a train of cars of the type having a locomotive and a rear car, a brake application and release signalling system comprising in combination a radio device on the locomotive and a radio device on the rear car, a first brake cylinder means on the locomotive and a second brake cylinder means on the rear car operative upon the supply of uid under pressure thereto to ciect a brake application on the locomotive and rear car respectively, a source of supply of uid under pressure, control means for controlling the supply of fluid under pressure from said source to the said first and second brake cylinders, atirst pressure switchmeanslocated o'n the locomotive and operative responsively to a supply of fluid under pressure from said source to said first brake cylinder means, warning circuit means operatively controlled by said first pressure switch means to render said radio device on the locomotive effective to transmit a signal to said radio device on the rear car, a second pressure switch means located on the rear car and operative to a closed position responsively to a supply of fluid under pressure from said source to said second brake cylinder means, and operative to a closed position responsively to initiation of a release of said brake-applying fluid pressure from said second brake cylinder means, and answering circuit means operatively controlled by said second pressure switch in said closed position to render said radio device on the rear car effective to transmit a signal to said radio device on the locomotive.

16. For use on a train of cars of the type having a locomotive and a rear car, a brake application and release signalling system comprising in combination a radio device on the locomotive and a radio device on the rear car, a first brake cylinder means on the locomotive and a second brake cylinder means on the rear car operative responsively to supply of fluid under pressure thereto to effect a brake application on the locomotive and rear car respectively, a source of supply of fluid under pressure on the locomotive and cars, control means for controlling the supply of fluid under pressure from said source to the first and second brake cylinders, warning circuit means effective when energized to cause said radio device on the locomotive to operate to transmit a warning signal to the radio device on the rear car, first pressure responsive means subject to the fluid under pressure in said first brake cylinder at a predetermined rate of supply immediately upon initiation of a brake application, second pressure responsive means subject to supply of fluid under pressure in said rst brake cylinder at a slower rate than said predetermined rate of supply after initiation of a brake application, and switch means included in said warning circuit means operable responsively to a differential of pressures acting in opposition to each other on said rst pressure responsive means and said second pressure responsive means to render said warning circuit energized and operable responsively to equalization of the pressures acting in opposition to each other on said first and second pressure responsive means to render said Warning circuit deenergized, answering circuit means effective when energized to cause said radio device on the rear car to operate to transmit an answerV signal to said radio device on the locomotive, and pressure switch means included in said answering circuit means operative responsively to supply of uid under pressure to sad second brake cylinder to render said answering circuit energized.

17. For use on a train of cars of the type having a locomotive and a rear car, a brake application and release signalling system comprising in combination a rad'o device on the locomotive and a radio device on the rear car, a rst brake cylinder means on the locomotive and a second brake cylinder means on the rear car operative responsively to supply of fluid under pressure thereto to effect a brake application on the locomotive and rear car respectively, a source of supply of fluid under pressure on the locomotive and rear car, control means for controlling supply of fluid under pressure from said source to said first and second brake cylinders, warning circuit means effective when energized to cause said radfo device on the locomotive to operate to transmit a warning signal to the radio device on the rear car, first pressure responsive means subject to the uid under pressure in said rst brake cylinder at a predetermined rate of supply immediately upon initiation of a brake application, second pressure responsive means subject to supply of fluid under pressure in said first brake cylinder at a slower rate than said predetermined rate of supply after initiation of a brake application, and switch means included in said warning circuit means operable responsively to a diiierential of pressures acting in opposition to each other on said first pressure responsive means and said second pressure responsive means to render said warning circuit energized and operable responsively to equalization of the pressures acting in opposition to each other on said irst and second pressure responsive means to render said warning circuit deenergized, answering circuit means eilective when energized to cause said radio device on the rear car to operate to transmit an answer signal to said radio `device on the locomotive, pressure switch means included in said answering circuit means subject to supply of liuid under pressure in said second brake cylinder during a brake application, said pressure switch means operative responsiveiy to initiation of suppiy of tluid under pressure thereto to render said answering circuit energized and operative responsively to'completion of supply of uid under pressure thereto to render said answering circuit deenergized.

18. For use on a train of cars of the type having a locomotive and a rear car, `a brake application and release signalling system comprising in combination a radio device on the locomotive and a radio device on the rear car, a iirst brake cylinder means on the locomotive and a second brake cylinder means on the rear car operative responsively to supply of uid under pressure thereto to eiect a brake application on the locomotive and rear car respectively, a source of supply of liuid under pressure to the locomotive and rear car, control valve means for controlling the supply of iiuid under pressure from said source to said rst and Second brake cylinders, Warning circuit means effective when energized to cause said radio device on the locomotive to operate to transmit a warning signal to the radio device on the rear car, rst pressure responsive means subject to the fluid under pressure in said irst brake cylinder at a predetermined rate of supply immediately upon initiation of a brake application, second pressure responsive means subject to supply of fluid under pressure in said irst brake cylinder at a slower rate than said predetermined rate of supply after initiation of a brake application, choke means operative to delay the rate of supply of fluid under pressure to said second pressure responsive means, switch means included in said warning circuit means operable responsively to a diierential of pressures acting in opposition to each other on said first pressure responsive means `and said second pressure responsive means to render said warning circuit energized and `operable responsively to equalization ofthe pressures acting in opposition to each other on said rst and second pressure responsive means to render said warning circuit deenergized, answering circuit means effective when energized to cause said radio device on the rear car to operate to transmit an answer signal to the radio device on the locomotive, and pressure switch means included in said answering circuit subject to supply of uid under pressure in said second brake cylinder, said pressure switch means being operative responsively to initiation of supply of fluid under pressure thereto to render said answering circuit energized and operative responsively to completion of supply of fluid under pressure thereto to render said answering circuit deenergized, said pressure switch means also operative responsively to initiation of release of uid under pressure therefrom to render said answering circuit energized and operative responsively to completion of release of uid under pressure therefrom to render said answering circuit ldeenergized.

19. For use on a train of cars of the type having a locomotive and a rear car, a brarre application and release signalling system comprising in combination with a radio device on the locomotive and a radio device on the rear car, a rst brake cylinder means on the locomotive and a second brake cylinder means on the rear car operative upon supply of fluid under pressure thereto to effect a brake application on the locomotive and rear car respectively, a source of supply of iluid under pressure on the locomotive and rear car, control means for controlling the supply of iiuid under pressure from said source to said first and second brake cylinders, warning circuit means effective when energized to cause said radio device on the 1iocornotive to operate to transmit a warning signal to the radio device on the rear car, iirst microphone circuit means effective when energized to cause said radio device on the locomotive to operate to transmit voice communication to the radio device on the rear car, rst pressure responsive means subject to the i'luid under pressure in said iirst brake cylinder at a predetermined rate of supply immediately upon initiation of a brake application, second pressure responsive means subject to iluid under pressure in said iirst brake cylinder at a slower rate than said predetermined rate of supply after initiation of a brake application, choke means positioned between said second pressure responsive means and said first brake cylinder to edect delay of rate of supply of iiuid under pressure therebetween, and switch means included in said warning circuit means operable responsively to a differential of pressures acting in opposition to each other on said iirst pressure responsive means and said second pressure responsive means to render said warning circuit energized and operable responsively to equalization of the pressures acting in opposition to each other on said rst and second pressure responsive means to render said warning circuit deenergized, first selector switch means manually operative for selectively rendering said warning circuit deenergized and said first microphone circuit energized irrespective ofthe positioning of said switch means, answering circuit means effective when energized to cause said radio device on the rear car to operate to transmit an answer signal to the radio device on the locomotive, second microphone circuit means effective when energized to cause said radio device on the rear car to operate to transmit voice communication to the radio device on the locomotive, pressure switch means included in said answering circuit subject to supply of fluid under pressure in said second brake cylinder, said pressure switch means -operative responsively to initiation of supply of fluid under pressure thereto to render said answering circuit energized and operative responsively to completion of supply of iiuid under pressure thereto to render said answering circuit deenergized, said pressure switch means also operative responsively to initiation of release of uid under pressure therefrom to render said answering circuit energized and operative responsively to complete release of fluid under pressure therefrom to render said answering circuit deenergized, and second selector switch means for selectively rendering said answering circuit deenergized and said second microphone circuit energized irrespective of the operation of said pressure switch means.

No references cited. 

